限量灌溉对石羊河流域春小麦根区水氮迁移和利用的影响

Effects of limited irrigation on water and nitrogen transport and use in spring wheat rootzone soil in Shiyang River basin

为了探讨西北旱区春小麦最佳的水氮耦合形式,在甘肃石羊河流域绿洲区进行了田间试验,研究了限量灌溉对作物根区的水氮迁移动态和利用的影响。结果表明:在春小麦拔节以前各灌水处理的根区土壤硝态氮累积主要集中在剖面0～40 cm处,其累积量都约为550 kg/hm2。播后62 d起高水处理在根区土壤硝态氮开始出现了淋失,其硝态氮累积量是特低水处理在整个剖面上累积量的0.76倍。收获时根区土壤硝态氮的残留量特低水处理>低水处理>中水处理>高水处理,其中特低水处理的残留量是高水处理的1.75倍。除拔节期以前,根区土壤硝态氮的累积量和土壤水贮量呈线性递减关系。高水处理比中水处理的产量高约4%,而灌水量比中水处理高约30%。在水资源严重亏缺的条件下,春小麦全生育期灌水360～280 mm可以保证有较高的产量和较高的水分利用效率。

The objective of this study is to explore the best coupling form of water and nitrogen in arid areas of northwest China. A field experiment was conducted in the oasis region of Shiyang River basin, and the effects of limited irrigation on water and nitrogen transport and use in spring wheat rootzone soil were investigated. The results showed that NO3^- - N accumulation in root soil was mainly concentrated in the 0-40 cm profile before the jointing stage and the accumulation was about 550 kg/hm^2. NO3^- - N was leaching in the rootzone soil of high water treatment from 62 days after sowing, and the NO3^- - N accumulation of high water treatment was 0.76 times of that of lower treatment in the profile. The residual NO3^- - N of lower water〉low water〉middle water〉high water at harvest time, and the residues of lower water treatment is 1.75 times of that of high treatment. A linear decreasing correlation existed in the accumulation of NO3^- - N and soil water storage after jointing stage. The yield of high water was higher than that of middle water by 4 %, while the amount of irrigation was higher by 30 %. The irrigation amount of 360-280 mm in the whole growth period could guarantee yield and water use efficiency on the condition of deficit water resources.